Electrolytic chemical process

ABSTRACT

THE INVENTION COMPRISES THE USE OF A DIAPHRAGMLESS, ALTERNATING CURRENT ELECTRILYTIC CELL FOR THE CONDUCTING OF IRREVERSIBLE CHEMICAL REDUCTIONS OR OXIDATIONS. THE ELECTROLYTIC CELL IS USED TO GENERATE AN INTERMEDIATE THAT IS REACTIVE WITH THE REACTANT TO FORM A CHEMICAL PRODUCT. THE REACTION IS PREFORMED IN THE ELECTROCHEMICAL CELL UNDER IRREVERSIBLE CONDITIONS. IN A SPECIFIC EMBODIMENT THE REACTION IS APPLIED TO THE OXIDATION OF OLEFINS USING AN ELECTROLYTE CONTAINING A GROUP VIII NOBLE METAL AND SUFFICIENT DISSOLVED SALTS FOR PROVIDING THE DESIRED CONDUCTIVITY BETWEEN THE ELECTRODES. THE REACTION CAN BE PREFORMED IN AQUEOUS ACIDS, ORGANIC CARBOXYLIC ACIDS, ALCOHOLIC ELECTROLYTES, ETC., AND THE PRODUCT OF THE OXIDATION DEPENDS UPON THE CHOICE OF THIS MEDIUM. USE OF AQUEOUS ELECTROLYTES RESULTS IN THE FORMATION OF UNSATURATED CARBOXYLATES; AND USE OF ALCOHOLIC REACTION MEDIA RESULT IN THE FORMATION OF ACETALS AND UNSATURATED ETHER. EXAMPLES OF SPECIFIC USE ARE THE OXIDATIONS OF ETHYLENE OT ACETALDEHYDE AND/OR VINYL ACETATE; OR DIMETHYL ACETAL.

D. C. YOUNG Filed Oct. 16, 1967 ELECTROLYTIC CHEMICAL PROCESS Feb. 2,-1971 u m b we v u. w C o r r W l W 1 a I r M N \MQMYMRQN INVENTOR. DOA4L0 6'. YOU BY V g? FREQVE/VCY-(AOMI/IHM/C 5:445)

fiauaa United States Patent 3,560,354 ELECTROLYTIC CHEMICAL PROCESSDonald C. Young, Fullerton, Calif., assignor to Union Oil Company ofCalifornia, Los Angeles, Calif., a corporation of California Filed Oct.16, 1967, Ser. No. 675,534 Int. Cl. C07b 3/00 US. Cl. 204-80 10 ClaimsABSTRACT OF THE DISCLOSURE The invention comprises the use of adiaphragmless, alternating current electrolytic cell for the conductingof irreversible chemical reductions or oxidationsv The electrolytic cellis used to generate an intermediate that is reactive with the reactantto form a chemical product. The reaction is performed in theelectrochemical cell under irreversible conditions. In a specificembodiment the reaction is applied to the oxidation of olefins using anelectrolyte containing a Group VIII noble metal and sufficient dissolvedsalts for providing the desired conductivity between the electrodes. Thereaction can be performed in aqueous acids, organic carboxylic acids,alcoholic electrolytes, etc., and the product of the oxidation dependsupon the choice of this medium. Use of aqueous electrolytes results inthe formation of unsaturated carboxylates; and use of alcoholic reactionmedia results in the formation of acetals and unsaturated ethers.Examples of specific use are the oxidations of ethylene to acetaldehydeand/ or vinyl acetate; or dimethyl acetal.

The cell is operated at relatively mild conditions of temperatures from30350 C. and pressures from atmospheric to about 1000 atmospheres, thehigher pressures being employed for gaseous reactants. The chemicalreaction is irreversible while the companion electrochemical reaction ismade irreversible by application of a potential which exceeds the overvoltage of the particular electrochemical reaction. In this manner it ispossible to operate the cell without a diaphragm and to achieveelficient utilization of the electrical energy input to the electrolyticcell. The electrolyte is agitated during the reaction and a highconcentration of the chemically reacting species is maintained to insurethis reaction favorably competes with the undesired, competingelectrolytic reaction.

DESCRIPTION OF THE INVENTION The invention relates to the electrolyticprocessing of organic compounds and comprises the application of adiaphragmless electrolytic cell having an input electrical alternatingcurent potential. The electrolytic cell is applied to an irreversibleoxidation or reduction of a chemical reactant to produce a usefulproduct involving the electrolytic generation of an intermediate neededfor the reaction. The companion oxidation or reduction reaction whichoccurs in the cell is maintained irreversible by the application of asufficient potential that exceeds the over voltage of the particularreaction.

Chemical processing in eletcrolytic cells separated into two chamberswith a diaphragm has been applied to a number of chemical reactions. Thecathode and anode are placed in the separate chambers which are filledwith their respective electrolyte solutions and electrical conductivityis maintained between the chambers by use of a salt bridge or through adiaphragm which is permeable to an ionic species in the electrolyte,typically permeable to protons. The diaphragms are used to insure thatthe desired reaction occurs by preventing diffusion of other ionsbetween the electrodes. One of the disadvantages of the separatedelectrode cell is the relatively high potential drop across thediaphragm which results in a large power requirement for the reaction.Diaphragms in electrolytic cells also have a high maintenancerequirement. The diaphragms generaly are structurally weak and only verymoderate pressure differentials can be maintained across the diaphragm.This often precludes the use of high pressures in the chamber containingthe chemically reactive species despite the obvious advantage that theapplication of superatmospheric pressures would have on the reaction.

I have now found that the objectionable diaphragm in electrolytic cellswhere a reaction intermediate is electrolyticaly generated can beeliminated by the use of an alternating current potential which isapplied to the electrodes provided that the reactions which occur in theelectrolytic cell are irreversible. Generally the desiredelectrochemical reaction that produces a useful product is irreversible.The companion electrolytic reaction is made irreversible by theapplication of a potential which exceeds the over potential of theparticular electrochemical reaction. In this manner reversibility iseliminated and the application of an alternating current potential tothe cell is feasible and can result in an efiicient eletcrolytic celloperation.

The method of my invention is applied to a reaction wherein a reactionintermediate can be electrolytically generated. The intermediate can bean oxidized intermediate such as a peroxide, hydroperoxide or an olefincomplexing metal cation. Typical of such olefin complexing metals arethe Group VIII noble metals, mercury, thallium, silver, etc. Thesemetals exhibit the ability to form pi-complexes with olefins and thesepi-complexes are decomposable in the presence of a suitable reactive 7species to produce a substituted olefin with resultant reductingspecies, e.g., a soluble salt, can also be present.

The reduced form of the pi-complexing metal is electrolyticaly oxidizedin the cell, and chemical reduction by reaction with the olefiniccompound rather than electrochemical reduction of the pi-complexingmetal by the reverse potential is insured by maintaining an environmentin the electrolyte that is highly concentrated with the olefiniccompound. The companion electrochemical reduction which occurs with theoxidation of the olefinic compound is generally the reduction of protonsto hydrogen. To insure that this electrolytical reduction isirreversible the potential applied to the electrodes exceeds the overpotential of the hydrogen at the electrodes so that the hydrogen formedis evolved as hydrogen gas from the eletcrolytic cell.

Preferably, the electrolyte is maintained under moderate to severeagitation to insure mobility of the reduced species of the pi-complexingmetal and to insure thorough contacting of the olefinic compound withthe high valency state of the pi-complexing metal.

The efficiency of the electrochemical cell is influenced considerably byits size and design. Significant factors in the design of theelectrolytic cellwhich are interrelated are the spacings between theelectrodes, the degree of agitation applied to the electrolyte, theconductivity of the cell and the mobility of the ions and pi-complexingmetal in the solution. The latter characteristic is affected by thestate of the pi-complexing metal, e.g., metallic form, or ionic as wellas the solutions viscosity, tempera- 3 maximum. This optimum alternatingcurrent frequency can be readily determined by operation of the cellthroughout a range of frequencies while observing the yield of productat each frequency setting.

When a potential is applied between electrodes immersed in a conductingliquid there is an envelope of the solution in close proximity abouteach electrode Where the current carrying species, typically dissolvedor solvated ions, freely transfer their charges to the electrodes.Diffusion of ions between these envelopes and the bulk of the solutiondepends on the mobility of the various ions in the liquid.

The figure illustrates a typical efiiciency-frequency relationship in anelectrochemical cell of my invention. The efiiciency is plotted on theordinate and is the quotient of the gram equivalent weight of productobtained during a time period divided by the Faradays of electricalinput over that time period. The relationship is shown as two curves,a-b and bc which intersect as shown. Curve ab will intercept theordinate at cycles per hour (direct current condition) while curve b-capproaches the abscissa at the maximum frequency. At the ordinateintercept, infinite time is available to permit difiusion andequilibrium of the cell. Some product is obtained and the resultantefficiency can be referred to as the saturation efiiciency and reflectsthe rate of the following reaction:

(1) wherein:

Y is a chemical reactant;

M is charged intermediate with x being the valency of the intermediate.

The competing electrolytic reaction, however, occurs as follows:

wherein:

F represents Faradays of electrical energy.

The value of the saturation efficiency and position of curve a-b dependson variables which influence the rate of reactions 1 and 2. Increasingthe concentration of Y, e.g., by use of superatmospheric pressures inthe event that Y is a gaseous reactant or by changing other reactionconditions such as temperature, agitation of the liquid, etc., willprovide efliciencies following related curves a'b and a"b" shown indashed lines.

The efliciency of the cell increases, as shown, with reversal of theapplied EMF whenever a finite amount of species M is maintained in theliquid. Typically, M is a metal, often a precious metal, and the amountused in a cell is limited. At the electrode wherein the activeintermediate M is generated, a high concentration of M is initiallyformed. At the initial high level of M in the envelope about thegenerating electrodes, the M ions are rapidly reacted at the interfacewith reactant Y so the cell has a high initial efliciency. Some ions Mhowever, will escape into the solution and be decomposed at the oppositeelectrode. The available source of M is depleted by this electrolyticdecomposition of M to M at the opposite electrode. As this depletionoccurs the concentration of M about the generating electrode decreasesrelative to the concentration of M in the solution and the rate ofreaction (1) relative to reaction (2) also decreases so that the cellbecomes less eflicient.

When the applied EMF is frequently reversed the amount of time of thelow efiiciency (low M concentration) operation will be reduced and theaverage efiiciency during the particular half cycle will increase. Theincrease of this efiiciency with increasing frequency of the EMFreversal is shown as the positive slope of curve a-b. This curve a-b isthe chemical reactivity curve.

Curve bc represents the limit to the direct relationship of efiiciencyand frequency shown in curve a-b. This curve is the diffusion limitcurve and reflects internal cycling of the MSM reaction within the envelp about the electrodes. As the frequency of EMF reversal increases itapproaches a value Where the generated M ions do not reach the interfacebetween the electrode envelope and the solution and therefore can notreact with Y during the generating half cycle. In the succeeding halfcycle these M ions are decomposed to M with a resultant loss inefiiciency which increases with increasing frequency. The curve bcillustrates this relationship. A series of related curves b'-c' andb"-c" with progressively increasing mobility of the ions M and/ordecreasing thickness of the envelope is shown by the dashed linessuperimposed on curve bc.

From the preceding discussion, it is apparent that efficiency of thecell can also be maximized by decreasing the thickness of the envelopesurrounding the electrodes, e.g., by decreasing the solution viscosity,increasing its temperature, etc., or by increasing the mobility of the Mspecies, e.g., by avoiding bulky ligands or other components that maycomplex with M ions and retard their movement.

Olefins that can be reacted in accordance with my invention in generalcomprise any olefin having the following structure:

R R C:CHR wherein:

R R and R are selected from the class consisting of hydrogen, alkyl,cycloalkyl, aryl, alkaryl, aralkyl, alkanyl alkyl, alkanyl aryl, halo,halo alkyl, halo aryl, carboxyl, carboxyl alkyl, carboxyl aryl, acyloxy,nitroaryl and alkylene wherein two of said R R and R groups comprises acommon alkylene group.

Examples of useful olefins are: the aliphatic hydrocarbon olefins suchas ethylene, propylene, butene-l, butene-2, pentene-2, Z-methylbutene-l,hexene-l, octene-3,

r 2-propylhexene-1, decene-2, 4,4'-dimethylnonene-1, dodecene-l,6-propyldecene-l, tetradecene-4, 7-amyldecene-3, hexadecene-l,4-ethyltridecene-2, octadecene-l, 5,5-dipropyldodecene-3, eicosene-7,etc. Of these the aliphatic hydrocarbon olefins having from 2 to about 6carbons are preferred.

Other olefins include: vinylcyclohexane, allylcyclohexane, styrene,p-methylstyrene, 0c methylstyrene, fl-methylstyrene, p-vinylcumene, 1vinylnaphthalene, 1,2-diphenylethylene, allylbenzene, 6-phenylhexene l,1,3-diphenylbutene-l, 3-benzylheptene-2, o-vinyl p-xylene,a-chlorostyrene, p-chlorostyrene, m-nitrostyrene, divinylbenzene,l-allyl,4-vinylbenzene, 1,5-heptadiene, 2,5-decadiene, vinyl chloride,vinylidene dichloride, vinyl fluoride, trichloroethylene,trifluoroethylene, di(chloromethyl)ethylene, propenyl chloride, acrylicacid, crotonic acid, maleic acid, p-vinylbenzoic acid,p-allylphenylacetic acid, vinyl acetate, vinyl propionate, propenylacetate, butenyl caproate, ethylidene diacetate, etc.

Also reactive are the cycloalkenes, their substituted derivatives andalkylene cycloalkanes including: cyclobutene, cyclopentene, cyclohexene,methylcyclohexene, amylcyclopentene, cycloheptene, cyclooctene,cyclodecene, methylenecyclohexane, ethylidene cyclohexane, propylidenecyclohexane, etc.

Examples of suitable olefin complexing metals that can be employed inthe electrolyte include the Group VIII noble metals comprising theplatinum subgroup of platinum, osmium and iridium as well as thepalladium subgroup of palladium, ruthenium and rhodium. Other complexingcompounds include rhenium, mercury, thallium, etc. These metals can beadded to the electrolyte as the metal, as a dissolved salt or as asoluble complex. Examples of suitable salts include the halides,nitrates, sulfates or carboxylates of lower molecular weight (C Ccarboxylic acids, etc. Examples of suitable chelating agents that can beused include acetylacetonate, citric acid, alkylene diamines, alkylenediamine tetracarboxylic acids and salts thereof, complexes ofcyclopentadienyl, cyclobutadienyl and the lower alkyl and phenylderivatives thereof such as tetraphenyl cyclobutadienyl, etc. The metalscan also be added to the reaction medium as the oxide. Examples ofsuitable salts or oxides as aforedescribed include platinum chloride,palladium bromide, osmium fluoride, iridium bromide, ruthenium oxide,rhenium oxide, mercuric sulfate, palladium acetate, platinum propionate,iridium benzoate, osmium caproate, ammonium perrhenate, etc.

Since the complexing metal is employed as an electron transferringreactant, relatively minor quantities of the metal can be employed. Theelectrolytic cell therefore is operative with electrolytes containing aslittle as 0.001 weight percent of the complexing metal. Higherquantities of the complexing metal can of course be employed up to andexceeding the solubility of the particular salt of the complexing metalin the electrolyte. Generally, concentrations up to about 25 percent canbe employed; however, I prefer to use concentrations of the complexingmetal expressed as the metal from about 0.5 to about weight percent.

The electrolyte can also contain other dissolved salts to increase itselectrical conductivity. Examples of suitable dissolved salts includethe alkali metal, alkaline earth metal, and multivalent transition metalsoluble salts including the halides, sulfates, nitrates, C -Ccarboxylates etc. Examples of such salts include potassium chloride,sodium acetate, lithium nitrate, calcium chloride, barium nitrate,cupric chloride, ferric chloride, vanadyl sulfate, chromium nitrate,etc. The amount of the additional salt employed for conductivity throughthe electrolyte can vary from about 1 to about 50 weight percent,preferably from about 1 to about weight percent.

In the electrolytic cell the reactants that can be employed besides orinstead of the aforementioned olefins include carboxylic acids andsoluble salts thereof, alcohols, alkylamines, water, etc. The particularreactant depends upon the desired conversion, e.g., olefins can beoxidized in the presence of aqueous mineral acids of pH values from 0 to7 to produce carbonyl products; in the presence of organic carboxylicacids to produce unsaturated carboxylates; and in the presence ofanhydrous alkanols to produce alkoxy derivatives. With an olefin as thereactant and a Group VIII noble metal salt in the electrolyte, thefollowing electrolytes can be employed to produce the indicatedproducts: aqueous mineral acids including aqueous sulfuric, nitrichydrohalic acids such as hydrochloric, hydrobromic, hydrofluoric andhydriodic acid to produce carbonyls such as acetaldehyde, acetone,methylethyl ketone, etc. from respectively, ethylene, proplene, butene-1, etc. The use of carboxylic acids as the reaction medium such asacetic, propionic, isobutyric, butyric, valeric, pivalic, caproic,caprylic, decanoic, benzoic, phthalic, naphthoic, toluic, etc. resultsin the production of an unsaturated ester of the carboxylic acid. Theproducts are the vinylcarboxylates when the olefin is ethylene, e.g.,vinyl acetate from ethylene and acetic acid; allyl and propenyl productsare obtained by the oxidation of propylene; etc. When the reactionmedium comprises an anhydrous alcohol, the olefins can be oxidized toalkoxy derivatives, e.g., acetals are obtained from the reaction ofolefins and alcohols such as dimethyl acetal, diethyl acetal, dibutylacetal, from the reaction of ethylene and alcohols such as methanol,ethanol and n-butanol. Examples of suitable alcohols that can be usedfor the reaction include the alkanols such as methyl, ethyl, propyl,isopropyl, butyl, amyl alcohols, heptanol, octanol, decanol, etc.

Other reactions that can be performed, particularl in the presence ofmercury salts and mercuric oxide in the reaction medium comprise thecarbonylation of alcohols to produce alkyl carbonates, resulting in thestoichiometric reduction of the mercuric salt or oxide to the freemetal. The resultant metal is reoxidized to mercuric compound or oxideby the electrolytic cell.

The carbonylation of amines to prepare substituted ureas can also bepracticed in the electrolytic cell. In this reaction a primary orsecondary amine can be carbonylated by contacting the amine with carbonmonoxide in the presence of the mercuric ions to produce a substitutedurea with the resultant production of mercury and protons. The mercuryis regenerated in the electrolyic cell and the protons are reduced tohydrogen and evolved from the cell. This reaction can be employed on anyprimary or secondary alkyl, alkaryl, aryl amine such as methyl, ethyl,isopropyl, butyl, isoamyl, hexyl, isoheptyl, octyl, nonyl, isodecylamine, aniline, p-methyl aniline, o-ethyl aniline, m-butyl aniline,p-hexyl aniline, 2,5-xylidine, dimethylamine, dipropylamine,N.N-rnethylethylamine, N,N-ethylbutylamine, dihexylamine, N-methylaniline, N-butyl aniline, N-hexyl aniline, N-ethyl 2,5-xylidine,dipenylamine, di-p-tolylamine, di-otolylamine, pyrroline, piperidine,pyrizole, pyrrolidine, etc. It is of course apparent thatnon-symmetrical substituted ureas can also be obtained by the use ofmixtures of any of the aforementioned amines.

The reaction can also be applied to the oxidative carbonylation ofolefins, a reaction which is initiated by complexing of the olefin withany of the aforementioned Group VIII noble metals, particularly with thepalladium salts, oxide or chelates. This reaction is practiced by thesimultaneous introduction of carbon monoxide and the olefin into theelectrolytic cell which can contain a carboxylic acid or alcoholicelectrolyte. When the reaction medium comprises the carboxylic acid, thecarbonylation of the olefin results in the production of a mixture ofalpha, beta-ethylenically unsaturated carboxylic acids having one morecarbon atom than the olefin and betaacyloxy substituted acids thereofwherein the carboxylic acid solvent adds across the ethylenicallyunsaturated bond. When this reaction is performed in an alcoholicmedium, the resultant product is the ester of the aforementioned alpha,beta-ethylenically unsaturated bond. Examples of suitable conversionswith olefins include the production of acrylic and beta-acetoxypropionic acid by the reaction of ethylene with an acetic acid reactionmedium containing the Group VIII noble metal salt. Other examplesinclude the production of methacrylic and crotonic acids by the reactionof propylene as well as the production of the beta acyloxy derivativesthereof. When the reaction is performed in an alcohol such as ethanol,the resultant acids are esterified to produce, e.g., ethyl acrylate,beta-ethoxy ethyl propionate, isopropyl methacrylate, etc.

The reactions are performed at temperatures from about 30300 0,preferably from about -250 C. The pressure in the electrolytic cell canbe from atmospheric to superatmospheric, up to about 1500 atmospheres;preferably from about 10 to about 150 atmospheres. The higher pressuresare preferred when a gaseous reactant is employed such as ethylene,propylene, carbon monoxide, etc. The absence of a diaphragm simplifiesthe cell design and permits use of the cell at the aforementioned highpressures. The voltage applied to the electrodes of the electrolyticcell can be varied over a wide range; however, care should be taken notto exceed the over voltage of undesired electrolytic reactions. Ingeneral, the oxidations that produce the desired chemical productsrequire the accompanying reduction of hydrogen in the cell. To insureirreversibility of this reaction, the applied voltage under suchcircumstances should exceed the over voltage for the evolution ofhydrogen from the cell. Generally, voltages from about 1 to about volts,preferably from about 2 to about 10 volts, can be employed. Theelectrodes are positioned in the electrolytic cell with a sufficientspacing to permit the necessary conductivity in the cell and to providea reaction zone between the electrodes for the reacting species.

The particular frequency that achieves maximum cell efiiciency variesconsiderably depending on the cell design and ion mobility in the mannerpreviously described. The cells usually will be most efficient whenoperated over a frequency of from 0.5 to 200,000 cycles per hour. The

lower frequencies will most probably be most efficient and I prefer touse frequencies from about 2 to 1000 cycles per hour.

The invention will now be described by reference to the followingexample:

EXAMPLE The electrolytic oxidation of ethylene to acetaldehyde wasperformed in a diaphragmless cell using a low frequency alternatingcurrent. The electrolytic cell comprised a glass flask containing anelectrolyte and two parallel carbon plates approximately 7 x inches thatwere s aced one inch apart. Provision was made to stir the electrolytein the electrolytic cell which comprised a. 2 percent solution ofsulfuric acid containing 1 weight percent palladium chloride. Provisionwas made for the introduction of ethylene between the carbon plates andthe exit connection from the flask was passed through a reflux condenserand two product traps including an acetone-dry ice trap for thecondensation of the acetaldehyde product. The cell washeated to raisethe contents to reflux temperature and ethylene was introduced into thecell while stirring the electrolyte. An alternating current of amps. waspassed through the cell at varied frequencies of the applied voltagefrom /2 cycle per hour to 60 cycles per second while the stirring rate,temperature and other variables 'were maintained constant. At theseconditions the following reaction efficiencies, expressed as mols ofproduct per equivalent mols of electrical input were obtained:

Cycles per hour Reaction efllciency The preceding data demonstrate thatan optimum cycle of frequency for the alternating current exists andthat for the particular cell under investigation this optimum cycle wasat about 10 cycles per hour. Simultaneous with the production of theacetaldehyde was the reduction of protons at the electrode andproduction of hydrogen which was removed in the mixed gas streamcontaining the acetaldehyde.

Substantially the same results can be achieved by the use of othermetals such as aforedescribed in the electrolyte or the use of any ofthe other aforementioned olefins or reactants. Similarly, substantiallythe same operation of the cell can be applied to the oxidativecarbonylation of olefins by the simultaneous introduction of carbonmonoxide into the electrolytic cell. Higher molecular weight olefinsthan ethylene can be reacted by charging them to the electrolytic cell,e.g., by substituting propylene for the ethylene introduction or byadding to the electrolyte a higher boiling olefin such as octene,decene, etc. Substitution of the electrolyte with an electrolytecomprising an amine containing mercuric oxide can be used in combinationwith the introduction of carbon monoxide for the production ofsubstituted ureas.

The preceding illustration of the invention is not intended to be undulylimiting of the invention but rather it is intended that the inventionbe defined by the steps and reagents and their obvious equivalents setforth in the following claims.

I claim:

1. The method for conducting an oxidation reaction in an electrolyticcell comprising an electrolytic chamber, an electrolyte containing asoluble oxidized reaction intermediate selected from the groupconsisting of a per- 8 oxide, a hydroperoxide and ions of platinum,osium, iridium, palladium, ruthenium, rhodium, rhenium, mercury andthallium maintained therein, and at least two electrodes within a commonchamber of said electrolytic cell which comprises contacting saidelectrolyte with a chemical reactant capable of reducing said oxidizedreaction intermediate in the electrolytic cell at a temperature fromabout 30 to 300 C. and at a pressure from about 1 to 1500 atmospheres toreduce said intermediate and form an oxidized product from said reactantand regenerating the reduced reaction intermediate to the oxidizedintermediate by applying to said electrodes an alternating cur rentpotential having a frequency between about 0.5 and 200,000 cycles perhour and suflicient voltage to exceed the over voltage of hydrogen.

2. The method of claim 1 wherein said oxidized reaction intermediatecomprises ions of a Group VIII noble metal, said reactant comprises anolefin and said electrolyte comprises a substituent tobe incorporated onsaid olefinic reactant.

3. The method of claim 2 wherein said olefin is ethylene, said GroupVIII noble metal is palladium and said electrolyte comprises an aqueousmineral acid selected from the group consisting of sulfuric, nitric,hydrochloric, hydrobromic, hydrofluoric and hydriodic acid.

4. The method of claim 3 wherein said olefin is ethylene, saidcomplexing metal is palladium, said electrolyte comprises asubstantially anhydrous carboxylic acid and said product is a vinylester.

5. The method of claim 3 wherein said olefin is methylene, saidcomplexing metal is palladium, said electrolyte comprises asubstantially anhydrous alkanol and the product of said reaction is adialkyl acetal.

6. The method for oxidizing an olefin in an electro lytic cell having atleast two electrodes inserted with a common chamber thereof whichcomprises:

introducing said olefin into said chamber and into contact with anaqueous electrolyte containing ions of platinum, osmium, iridium,palladium, ruthenium, rhodium, rhenium, mercury or thallium;

maintaining the temperature of said chamber at about 30 to 300 C. andthe pressure within said chamber from 1 to about 1500 atmospheres; and

simultaneously applying a continuous alternating potential across saidelectrodes at a frequency of between about 0.5 and 200,000 cycles perhour and at a sufiicient voltage to exceed the over voltage of hydrogenand to maintain said metal in said electrolyte as ions.

7. The method of claim 6 wherein said electrolyte also contains from 1to weight percent of a soluble salt of an alkali metal or an alkalineearth metal.

8. The method of claim 6 wherein said electrolyte comprises an aqueousmineral acid selected from the group consisting of sulfuric, nitric,hydrochloric, hydrobromic, hydrofluoric and hydriodic acid.

9. The method of claim 6 wherein said electrolyte contains palladiumions and wherein said olefin is an aliphatic hydrocarbon olefin havingfrom about 2 to about 6 carbons.

10. The method of claim *8 wherein said mineral acid is sulfuric acid.

References Cited UNITED STATES PATENTS 3,147,203 9/1964 Klass 204 JOHNH. MACK, Primary Examiner R. L. ANDREWS, Assistant Examiner US. Cl. XJR.204--72

